Braun tube



a Y 1 H. E. HOLLMANN 2,046,513

BRAUN .TUBE V Filed Feb. 23, 1935 CATHODE'RAY Pl E ANODE SCREEN q INVENTOR HANS ERICH HOLLMANN I Q/M/f JLM ATTORNEYS Patented July 7, 1936 1 owl-TED- STATES 'BRAUN TUBE. Hans Erich Hollmann, Berlin, Germany, assignor to Radio Patents Corp oration; New York, N. Y.,

a'corporation of New York Application February 23, 1933, Serial No. 657,935

In Germany May 3!), 1932 7 Claims. (o1.v 250-275) The present invention relates to an'improved Braun tube working. withoutdistortion even at very high frequencies and at all'speeds of electrons.

reference totheaccompanying drawing, in which ,Fig. 1 is a detailed view ofv a portion of 'a conventional Braun tube showing theaarrangement of two pairs of deflecting plates, and

Fig. 2 is a detailed view of a portion of a Braun tube constructed in I accordancefwith the present invention 'and' showingthe arrangement. of the three pairs of deflecting plates. j

While the conventional Braun tube such as shown in Figure 1 inwhich a cathode ray is generated in any well linown'manner and is passed through an aperture in the anode screen and between a pair of deflecting plates P1 and P2 works inertialess in a wide range of frequencies, the electron velocity makes itself injuriously noticeable when recording very high frequencies. If in such a Braun tube the two pairs of deflecting plates P1 and P2 are arranged in the direction of radiation at a distance it apart, as shown in Fig. 1 of the accompanying drawing, which has proved practical, partly for the climinuation of mutual capacities and partly for the production of a deflection field as uniform as possible, then the cathode ray is no longer uniform in both coordinate directions but is deflected by a phase displacement determined by the time t which the electrons take to move between the two pairs of plates. For a frequency a; this temporary retardation of the phase angle is =wt, and the time t may be derived from the distance d and the electron velocity v as d/v. If the two pairs of deflecting plates have the same alternating voltages, i. e. if the deflecting voltages are entirely in the same phase, then the straight line which normally appears on the light screen is drawn apart at very high frequencies to an ellipse, or if the phase angle amounts to 90 to a circle. Since the phase displacement is proportional to the sine of the phase angle it is always zero when the angle runs through integral (whole number) multiples of 1r. If reaches this critical value at corresponding frequencies or at corresponding accelerating voltages of the cathode ray, E an, the phase displacement is destroyed and with equal deflecting voltages a straight line again appears on the light screen.

For the time t between the two pairs of plates there results:-

The invention lwill be further described with v wherein X is the wave length in centimeters the phase angle 4) is obtained as:

which for the determination of the critcal voltage .EK, at which for the given frequency w the phase. distortion disappears, is equal to 1min which n represents a whole number. From this there is obtained for any wave length a series of critical anode voltages:

Inpracti g, the compensation of the phase distomes-by the accelerating voltage'E is naturally an undesirable complication, which is especially important when the frequency and tube dimensions are just such that the corresponding compensation voltage no longer gives fluorescence spots.

According to my invention the said drawback is avoided by splitting up the phase displacement (which is unavoidable per se) into two equal components having opposite signs. The two opposed phase rotations then cancel out so that a tube of the said kind works without distortion even at very high frequencies and at all speeds of the electrons.

A practical arrangement embodying the invention is shown in Fig. 2 of the accompanying drawing, but the invention is not restricted to the particular arrangement shown. In this figure the cathode ray is likewise produced in any convenient manner from a cathode I in a closed tube 2 of usual form, a portion of which is shown in the drawing, and is passed through an aperture 3 in an anode screen 4 in a manner similar to that indicated in Fig. 1. The ray then passes in section between three pairs of deflecting plates, P2, P1 and P2, respectively. The plates, P2 and P2" are disposed in the same plane which extends at right angles to the plane of the plates P1. The plates P2 and P2 are directly connected with each other and are arranged at equal distances d and d" on either side (i. e., in front and behind in the direction of the cathode ray) of the other pair of plates P1. While moving through the distance d there first of all takes place a phase rotation of the cathode ray an angle =wd'/'l), and while flowing through the distance d" an equal but reversed phase rotation takes place about an angle "=wd"/1J=', The two phase displacements thus compensate each other independently of the frequency or acceleration voltage, so that in all circumstances a straight line appears on the fluorescence screen when the two deflecting plates are in phase. A limit to the frequency is then only occasioned by the general condition that the dimensions of the deflectingelements must be small as compared with the wavelength.

What I claim is:

1. A Braun tube comprising a casing, a cathode i and an anode arranged to project a cathode ray along the axis of said casing, three pairs of ray deflecting plates arranged in sequence in the path of the ray, the first and the third pairs of plates being disposed in the same plane and connected in parallel whereby a high-frequency, deflecting potential, when supplied to them, deflects the cathode ray simultaneously and synchronously in the same direction, and the middle pair of plates being disposed in a plane at right angles to the plane of the other plates whereby a high-frequency deflecting potential, when supplied to them, deflects the cathode-ray in a vertical direction to the direction of the deflection of the other two pairs of plates.

first plane, said secondfieflecting means'comprising two portions connected with each other and arranged at opposite sides of said first defleeting means.

' v, 3. In an electronic device, means for producing means.

a cathode ray therein; and a deflecting system comprising a first deflecting means for deflectin said ray in a predetermined plane; a second deflecting means for deflecting said cathode ray a different plane being at an angle to said 5 first plane, said second deflecting means having :two portions connected with each other and arranged at equal distance from and at opposite sides of said first deflecting means.

; 4. electronic device, means for producl0 ing a cathode ray therein; and a deflecting system 'comprising a first deflecting means for deflecting said ray in a predetermined plane, a secondfideflecting means for deflecting said ray in a plane perpendicular .to said first plane, said 15 'second'deflectmg means "having two portions arranged at opposite sides or said first deflecting 5. In an electronic device, means for producmg a cathode ray thereingand a deflecting sys- 2 tem comprising a first deflecting means for defleeting said ray ina predetermined plane, a second deflecting means for'deflectin'g said ray in a plane perpendicular to said first plane, said -second deflecting meanshaving two portions con- 25 nectedwith each other and arranged at equal distance 'from' and atopposite sides of said first deflecting means;

mars amen n'ci MANN; 

